1. Field of the Invention
Embodiments of the invention relate to a liquid crystal display device, and more particularly, to a liquid crystal display device and a method of driving the same. Although embodiments of the invention are suitable for a wide scope of applications, they are particularly suitable for obtaining a liquid crystal display device including a discharging circuit and the method of driving the same.
2. Discussion of the Related Art
Liquid crystal display (LCD) devices use the optical anisotropy and polarization properties of liquid crystal molecules to produce an image. The liquid crystal molecules have long and thin shapes, and have the optical anisotropy property, such that the liquid crystal molecules can be aligned along an alignment direction. The liquid crystal molecules also have the polarization property, such that the alignment direction can be changed according to an intensity of an applied electric field. In particular, the arrangement of the liquid crystal molecules can be changed by varying the intensity of the electric field. Consequently, light transmittance of the liquid crystal molecules is controlled by the electric field, and the LCD device displays images due to the changes in light transmittance.
In general, an LCD device includes a liquid crystal panel and a driving circuit. The liquid crystal panel includes first and second substrates spaced apart from each other and a liquid crystal layer between the first and second substrates. The first substrate, which is commonly referred to as an array substrate, has a thin film transistor and a pixel electrode, and the second substrate, which is commonly referred to as a color filter substrate, has a color filter layer and a common electrode. The driving circuit electrically drives the liquid crystal panel. Since the LCD device is a non-emissive type device, the LCD device includes a light source, such as a backlight unit, under the liquid crystal panel.
FIG. 1 is a schematic diagram illustrating an LCD device according to the related art. In FIG. 1, an LCD device includes a liquid crystal panel 10 and a driving circuit 60. The liquid crystal panel 10 includes a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm. The plurality of gate lines GL1 to GLn cross the plurality of data lines DL1 to DLm to define a plurality of pixel regions, and each pixel region includes a thin film transistor (TFT) T, a liquid crystal capacitor Clc and a storage capacitor Cst to display images.
The driving circuit 60 includes a timing controller 20, a gate driver 30, a data driver 40 and a power supply 50. The timing controller 20 generates data control signals for the data driver 40 including a plurality of data integrated circuits (ICs) and gate control signals for the gate driver 30 including a plurality of gate ICs using a plurality of external signals from an external system. Moreover, the timing controller 20 outputs data signals to the data driver 40.
The gate driver 30 controls ON/OFF operation of the thin film transistors (TFTs) in the liquid crystal panel 10 according to the gate control signals from the timing controller 20. On-level gate voltages are sequentially applied to the gate lines GL1 to GLn by a single horizontal synchronization time (1H) to enable the gate lines GL1 to GLn and the TFTs connected to the gate lines GL1 to GLn. When the TFTs corresponding to a single gate line are turned on, the data signals are applied to pixels in the pixel regions of the liquid crystal panel 10 through the data lines DL1 to DLm.
The data driver 40 selects reference voltages of the data signals according to the data control signals from the timing controller 20, and supplies the selected reference voltages to the liquid crystal panel 10 to adjust a rotation angle of liquid crystal molecules. The power supply 50 generates and supplies source voltages to the timing controller 20, the gate driver 30 and the data driver 40. In addition, the power supply 50 generates and supplies a common voltage to the liquid crystal panel 10.
When a power of the LCD device is off, the TFTs are also turned off. As a result, the data signals stored in the liquid crystal capacitor Clc and the storage capacitor Cst remain and are not discharged. Since the remaining data signals abnormally drives the liquid crystal panel for a short time, the liquid crystal panel displays undesired residual images or abnormal images.